On Mon, 3 Mar 2008, Douglas J Hunley wrote:
In other words, is it ok to checkpoint say, every 5 minutes, if it only last a second or three or better to have checkpoints every 10 minutes that last half a minute?
When checkpoints do too much work at once they will block clients for a significant period of time near the end--anywhere from 2 to 8 seconds isn't unusual. Every client on the system will just hang, then they all start responding again in a batch when the checkpoint is finished.
With that as the problematic case, if you can keep the duration of the checkpoint processing minimal by having them happen more frequently, then that's the better approach. You can't push that interval too small though or your system will be continuously checkpointing.
In cases where checkpoints hurt no matter how often you do them, there it makes sense to have them as infrequently as possible so at least you minimize the number of times that the disruption happens.
-- * Greg Smith gsmith@xxxxxxxxxxxxx http://www.gregsmith.com Baltimore, MD -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your Subscription: http://mail.postgresql.org/mj/mj_wwwusr?domain=postgresql.org&extra=pgsql-performance
